A need frequently arises for steps enabling a person to climb onto the bed of a pickup truck from the rear. Many pickup trucks have camper shells or other covers that form a barrier to access from the side. Some users, in particular, workmen who carry a load of tools, equipment, or supplies to a job site, may wish to climb on and off the bed many times during the course of a day, even if the bed is uncovered. The distance from a lowered tailgate to the ground is far enough to make climbing up or down inconvenient at best and dangerous when one's hands are occupied with carrying tools and the like.
Various types of unfolding step mechanisms for pickup truck tailgates have been disclosed previously. One approach, exemplified by U.S. Pat. Nos. 4,191,388 and 4,639,032, uses a U-shaped bar mounted on the inside of the tailgate, the bar being deployed by folding it downward over the outer edge of the tailgate. U.S. Pat. No. 3,961,809 discloses a step mechanism mounted on the outside of the tailgate, the steps moving downward for use by pivoting of linkage members around two horizontal shafts. The devices shown in these patents present a disadvantage in that they provide only one step between the ground and the tailgate, leaving a vertical distance substantially greater than for normal stair steps. A mechanism providing two steps is disclosed in U.S. Pat. No. 4,623,160, the steps being supported by a scissors-type system that folds up under the body of a recreational vehicle. Such mechanism, however, would not be practical for mounting on a tailgate. Another approach used for two-step ladders, as exemplified by U.S. Pat. No. 4,161,997, employs side frames that slide downward into contact with the ground for support. Such ladders fail to provide a firm footing where the surface of the ground is soft or irregular.
Desired features for a tailgate ladder assembly include simplicity of design and operation and a capability for providing more than one step. The assembly should also provide for easy movement of steps from stored to deployed position and back again. Once deployed, the steps should remain securely in position, with the steps spaced apart from one another and from the tailgate edge horizontally as well as vertically to facilitate climbing up and down them in the same manner as for a staircase.